1. Technical Field
The invention relates to hybrid electric vehicles. The invention further relates to silent key start, and to meeting climate control demands by the operator during silent key start.
2. Background Art
The use of mild and full hybrid electric vehicles is becoming widespread. A mild hybrid electric vehicle includes an integrated starter-generator (ISG). The ISG is used by an engine start-stop system. The engine start/stop system for a vehicle stops the internal combustion engine when the vehicle is stopped, and then starts the internal combustion engine when the driver requests acceleration. The engine also may be started, for example, due to loads on the electrical system or due to the catalyst temperature being low. For example, the internal combustion engine may be stopped when the vehicle stops at traffic lights or stops in a traffic jam. This approach is known as static start/stop. The stopping of the engine when the engine is not needed improves fuel economy, and reduces emissions. Although, sometimes, the engine may stay on when the vehicle is stopped because the alternator needs to run due to loads on the electrical system, or the engine may stay on for other reasons such as, for example, when the catalyst temperature is too low. In some approaches, fuel economy may be improved by 3-4% with static start/stop.
The ISG of the mild hybrid may also be utilized for regenerative braking, and may provide electric support drive assistance to the internal combustion engine. The mild hybrid, however, does not provide exclusive or full electric mode driving, which is the distinguishing feature from a full hybrid electric vehicle.
A feature related to start-stop systems and hybrid electric vehicles is silent key start. With silent key start, the internal combustion engine is not started when the key is turned on.
Some hybrid electric vehicles only charge the traction battery by running the internal combustion engine. Other hybrid electric vehicles are known as plugin hybrids, and allow the vehicle to be plugged into an electrical power source as a way to charge the traction battery.
Another feature of many modern vehicles is remote start. A remote start system allows the operator to start the vehicle remotely. Typically, this is done for climate control purposes. For example, an operator may remotely start the vehicle to heat or cool the vehicle interior prior to driving.
With the introduction of silent key start, remote start, plugin hybrids, or a combination of these, there is an issue with meeting the climate control demands with the internal combustion engine off, even if the ignition key is on or the vehicle has been remotely started.
For the foregoing reasons, there is a need for an approach to meeting climate control demands by the operator during silent key start.